This invention relates generally to filling a container with material, and more particularly concerns an vibratory powder filler for moving powders such as toner from a supply hopper through a fill tube to a container.
Currently when filling powders, for example toners into toner containers, toner is transported from the toner supply hopper into the container by a rotating auger. The auger is a spiral shaped mechanical part which pushes particles of toner inside a fill tube by direct mechanical contact. The nature of this mechanical contact process creates substantial limitations on accuracy and productivity of the toner filling operation. The speed of the toner movement in the fill tube is proportional to the speed of rotation of the auger and is limited by heat release due to auger/toner friction. High auger speed will cause the toner to melt, particularly for low melt toner such as disclosed in U.S. Pat. No. 5,227,460 to Mahabadi et al. the relevant portions thereof incorporated herein by reference.
Toner containers typically have a small opening into which the toner is to be added. Furthermore, the toner containers often have irregular shapes to conform to the allotted space within the copying machine. Therefore it becomes difficult to fill the toner container because of the small tube required to fit into the small toner container opening and secondly for all the toner within the container to completely fill the remote portions of the container before the container overflows.
The problems associated with controlling the filling of toner containers are due primarily to the properties of the toner. Toner is the image-forming material in a developer which when deposited by the field of an electrostatic charge becomes the visible record. There are two different types of developing systems known as one component and two component systems.
In one-component developing systems, the developer material is toner made of particles of magnetic material, usually iron, embedded in a black plastic resin. The iron enables the toner to be magnetically charged. In two-component systems, the developer material is comprised of toner which consists of small polymer or resin particles and a color agent, and carrier which consists of roughly spherical particles or beads usually made of steel. An electrostatic charge between the toner and the carrier bead causes the toner to cling to the carrier in the development process. Control of the flow of these small, abrasive and easily charged particles is very difficult.
The one component and two component systems utilize toner that is very difficult to flow. This is particularly true of the toner used in two component systems, but also for toner for single-component systems. The toner tends to cake and bridge within the hopper. This limits the flow of toner through the small tubes which are required for addition of the toner through the opening of the toner container. Also, this tendency to cake and bridge may cause air gaps to form in the container resulting in partial filling of the container.
Attempts to improve the flow of toner have also included the use of an external vibrating device to loosen the toner within the hopper. These vibrators are energy intensive, costly and not entirely effective and consistent. Furthermore, they tend to cause the toner to cloud causing dirt to accumulate around the filling operation.
The following disclosures may be relevant to various aspects of the present invention:
The relevant portions of the foregoing disclosures may be briefly summarized as follows:
U.S. Pat. No. 5,337,794 describes a powder filling apparatus and a method for filling a container with powder. The toner container is filled by conveying toner from a supply hopper through a nozzle with a valve on the end. The valve is disposed at the bottom opening of the nozzle to release and close the opening of the nozzle by the vertical movement of the valve element.
U.S. Pat. No. 5,438,396 is drawn to a toner anti-dribble device which is attached to a toner container having a vertical fill tube and a rotatable auger for feeding toner into a toner container. The toner anti-dribble device also has a sleeve member engagable with the fill tube. A plurality of flexible insertion wires are inserted through the sleeve member into the toner container and disposed substantially perpendicular to the insertion direction of the toner. The arrangement of the wires positively prevents toner dribble between fills while being flexible enough to flex in proportion to the fill rate, which prevents fusing of the toner on the wires.
U.S. Pat. No. 5,095,338 teaches a developer which discharges used carrier particles using a magnetic valve. Discharge of developer material from the developer housing is controlled by a permanent magnet and an electromagnet positioned adjacent an exit port in the developer housing. The permanent magnet generates a magnetic flux field in the region of the exit port to form a developer material curtain which prevents the passage of developer material from the exit port. When the electromagnet is energized, it generates a magnetic flux field which attracts developer material from the developer material curtain. Upon de-energization of the electromagnet, the developer material attracted to it is discharged.
U.S. Pat. No. 4,977,428 discloses an electrographic printer having a pulse motor for driving an agitator. The agitator is built into the developer unit. The agitator is controlled during the initialization process of the apparatus by setting the rotational speed of the motor at a lower level upon startup of the motor. The lower speed results in higher torque to overcome solidification of the toner.
U.S. Pat. No. 4,932,355 discloses a method for removing a developer mix from a developing station with a magnetic closing device which is in the vicinity of a discharge opening in the developing station. In its energized condition, the magnetic closing device creates a magnetic field which acts on the developer mix to form a plug of developer mix in the region of the discharge opening. In the de-energized condition, the magnetic closing device releases the plug of developer mix.
U.S. Pat. No. 4,650,312 discloses a structure for minimizing bridging or packing of toner in the flights of an auger of a toner removal and collection system. The toner anti-bridging structure includes a pendulum which is caused to periodically bang in to the auger to create vibrations in the auger structure.
U.S. Pat. No. 4,561,759 discloses a device for filling and filtering toner from a supply container. A filter basket is disposed in the region of the filling opening which is closed from the feed container by a filter mesh and an electric vibrator connected thereto by a linkage which can be automatically triggered at the beginning of a filling operation.
U.S. Pat. No. 5,839,485 which is assigned to the same assignee as the present application, teaches a method and apparatus for filling a container with a magnetic material using an electromagnetic valve and a demagnetizing circuit to control the flow and properties of the material. In the filling process an auger located inside of the fill tube rotates and moves the material through the fill tube. When the container is filled, the auger stops rotating and the electromagnetic valve is actuated. The electromagnetic valve supplies a magnetic field which holds the material in place, plugging the fill tube with the material as the container is removed and a new container is placed to be filled. When the electromagnetic valve is switched off, a demagnetizing circuit is activated. After the material is demagnetized the auger is switched on and the material flows again to fill the container.
U.S. Pat. No. 5,685,348 which is assigned to the same assignee as the present application, teaches a method and apparatus for filling a container with toner using a series of traveling magnetic fields to control the flow of toner from a supply of toner to the container. Initially, an empty container is placed under a fill tube through which the toner will be supplied to the container. In the filling process the traveling magnetic fields, which are supplied by turning on and off a series of solenoids, and gravity cause toner from the toner supply to move through the fill tube. When a solenoid is turned on toner particles are attracted to its magnetic field where a plug of toner is formed. The solenoids are controlled so that a discrete amount of toner is supplied in each on/off cycle of the solenoids. The solenoid on/off cycle is repeated until the container is filled with toner. When the container is filled, the appropriate solenoid is activated so that a plug of toner stops the flow of toner in the fill tube. The filled container is removed from the fill tube and an empty container is put in its place so that the solenoid on/off cycle may begin again.
U.S. patent application Ser. No. 08/823,034, which is assigned to the same assignee as the present application, teaches a method for filling a powder container is provided. The method includes the steps of placing a first powder container to be filled in filling relationship to a supply of powder in a vessel, mechanically exciting the powder in the vessel to improve its flow properties, dispensing powder from the vessel into the first container, removing the first container from the vessel, and placing a second container to be filled in filling relationship to the vessel.
U.S. patent application Ser. No. 08/829,925, which is assigned to the same assignee as the present application, teaches a method for filling a powder container is provided. The method includes the steps of placing a first powder container to be filled in filling relationship to a discharge feature in the vessel, directing the powder in the vessel toward a member located at least partially within the vessel, the member defining a restriction therein such that the powder clogs within the restriction, mechanically exciting the powder at least adjacent the restriction to improve the flow properties of the powder so as to unclog the powder within the restriction, dispensing powder through the restriction, through the discharge feature and into the first container, stopping the mechanical excitation of the powder so as to clog the restriction with the powder, removing the first container from the vessel, and placing a second container to be filled in filling relationship to the vessel.
U.S. patent application Ser. No. 08/923,016, which is assigned to the same assignee as the present application, teaches a method for filling a powder container with a supply of powder in a hopper. The method includes the steps of placing a first powder container to be filled in filling relationship to a conduit extending downwardly from the hopper, directing the powder in the hopper toward a nozzle in communication with the hopper, the nozzle defining a restriction therein, defining an inlet cross sectional area perpendicular to the flow the powder and outlet defining an outlet cross sectional area perpendicular to the flow the powder, selecting the inlet cross sectional area to be larger than the outlet cross sectional area, selecting the dimensions of said nozzle so as to provide a ratio of the inlet cross sectional area to the outlet cross sectional area of approximately two to one such that the flow of powder does not seize as it progresses through the nozzle, dispensing powder through the conduit, through the nozzle feature and into the first container, removing the first container from the hopper, and placing a second container to be filled in filling relationship to the hopper.
U.S. patent application Ser. No. 09/004,457, which is assigned to the same assignee as the present application, teaches an apparatus for controlling filling of a container from a hopper containing a supply of powder is provided. The apparatus includes a conduit for guiding the powder from the hopper toward the container. The conduit is operably associated with the hopper. The apparatus further includes a pliable member positioned at least partially within the conduit. The pliable member is positional into a first position wherein a passageway is formed within the conduit and into a second position wherein the pliable member serves to block flow of powder through the conduit, whereby said pliable member may controllably permit and block the flow of powder thorough said conduit.
Heat and Mass Transfer in a Moving Vibrofluidized Granular Bed teaches the study theoretically and experimentally of the drying rate of granular particles in the vibrofluidized bed dryer with mechanical vibrations. The combined effects of geometry, gas dynamics and thermal physical parameters were analyzed using the developed mathematical model. This model employs a coefficient which is determined experimentally and describes the drying rate at the falling rate period of drying. The results are compared with experimental data obtained for drying of sand particles in a one stage dryer.
Mechanics of Collisional Motion of Granular Materials teaches experimental data which revealed that for constant vibration amplitudes greater than 1 cm with a frequency increasing from 0, all layers of a granular particle pass through three vibrational states. The respective behaviors of these three vibrational states being as of (i) a solid plastic body, (ii) a liquid, (iii) a gas. In the liquid like vibration state, transferous waves propagate along the layer width. These waves were shown to be gravitational resonance waves, with the corresponding frequencies well correlated by the known formula for incompressible liquids. In the gas like vibrational state, compression (shock) an expansion wave propagation across the layer height were observed.
All of the above references are hereby incorporated by reference in their entirety
In accordance with one aspect of the present invention, there is provided a method for filling a powder container. The method includes the steps of placing a first powder container to be filled in filling relationship to a supply of powder in a vessel, vibrofluidizing the powder in the vessel to improve its flow properties, dispensing powder from the vessel into the first container, removing the first container from the vessel, and placing a second container to be filled in filling relationship to the vessel.
Pursuant to another aspect of the present invention, there is provided an apparatus for assisting the flow of powder from a hopper containing a supply of powder into a vessel. The apparatus includes a first member operably associated with the hopper and configured to be cyclically driven to vibrofluidize the powder.
Pursuant to yet another aspect of the present invention, there is provided an apparatus for assisting the flow of marking particles from a hopper containing a supply of marking particles into a vessel. The apparatus includes a first member operably associated with the hopper and configured to be cyclically driven to vibrofluidize the marking particles.